Kessler will take this as long as he isn't backed up.He has the advantages-hand speed,counter skills and a better defense.
Kessler has only looked bad against southpaws with good handspeed that have overwhelmed him.Froch has zilch handspeed and is right handed.
If Kessler gets his jab off first-he wins (think of Taylor/Froch without the stamina issues).Both fighters prefer to fight at arms reach of their opponents and are not good on the inside.
This is not a tough fight for Kessler-Froch has given me the impression that he is "ripe for the pickings".He has gotten extremely lucky against Taylor (who I view is not as good as Mikkel) and Dirrell.Froch always looks slow,but in the later rounds he looks even more sluggish-especially against Dirrell.
If this fight is purely based on styles,Kessler takes this... Froch (just like a majority of fans) probably believes Mikkel is a "shot or past-it" fighter,I believe he still has enough left-he has not been in severe wars apart from the Ward fight to really destroy him.His only major problem after the Calzaghe fight was inactivity...

Not that Froch is anything special, but he has more than enough to ko the one dimensional Kessler.

As one dimensional as Kessler is,Froch is even more so. Keep in mind that Kessler has more advantages and is better in technique.
I cannot think of one single time anyone has dropped Kessler-I believe he has a better chin and his better defense will take away from some of Froch's punches.
Froch will need that "puncher's chance" in this,but the problem is-Kessler hits hard as well...